1. Field
The present disclosure relates generally to wireless local area network (WLAN) systems, and more specifically, to the establishment of direct links between subscriber stations in WLAN systems.
2. Background
In many telecommunication systems, communication networks are used to exchange messages among several interacting spatially-separated devices. The various types of networks may be classified in different aspects. In one example, the geographic scope of the network may be over a wide area, a metropolitan area, a local area, or a personal area, and the corresponding networks may be designated as wide area networks (WANs), metropolitan area networks (MANs), local area networks (LANs), or personal area networks (PANs). Networks may also differ in the switching/routing technique used to interconnect the various network nodes and devices (e.g. circuit switching vs. packet switching), in the type of physical media employed for transmission (e.g. wired vs. wireless), or in the set of communication protocols used (e.g. Internet protocol suite, Synchronous Optical Networking, Ethernet, etc.).
One distinguishing characteristic between communication networks is the choice of wired or wireless media for the transmission of electrical signals among the constituents of the network. In the case of wired networks, tangible physical media such as copper wire, coaxial cable, fiber optic cable, etc., are employed to propagate guided electromagnetic waveforms that carry message traffic over a distance. Wired networks are a static form of communication networks and are typically favored for interconnection of fixed network elements or for bulk data transfer. For example, fiber optic cables may be the preferred transmission media for very high throughput transport applications over long distances between large network hubs, such as bulk data transport across or between continents over the Earth's surface.
On the other hand, wireless networks are often preferred when the network elements are mobile with dynamic connectivity needs or if the network architecture is formed in an ad hoc, rather than fixed, topology. Wireless networks may employ intangible physical media in an unguided propagation mode using electromagnetic waves in the radio, microwave, infra-red, optical, etc., frequency bands. Wireless networks have the distinct advantage of facilitating user mobility and rapid field deployment compared to fixed wired networks. However, usage of wireless propagation requires significant active resource management among the network users and higher levels of mutual coordination and cooperation for compatible spectrum utilization.
Accordingly, many wireless communication networks use Access Points (APs) to manage system resources among users, which may be referred to as subscriber stations or simply stations (STAs). Nevertheless, some wireless networking protocols provide for direct link communications among the STAs outside of the AP's mediation. This allows STAs associated with the same AP, for example, to set up a direct link between them. However, conventional discovery of other STAs capable of establishing a direct link has been based on the initiating STA detecting source and destination addresses, and sending a setup request without prior knowledge of the intended peer STA's capabilities.
There is therefore a need in the art for improved device discovery in establishing a direct link between STAs, so that a list of potential peer STAs that are direct-link capable may be discovered before attempting direct link setup.